<!DOCTYPE html>
<html lang="en">
<head>
	<title>hello</title>
</head>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>

<script type="text/javascript">
	$(function(){
		$("input").click(function(){
			console.log($(this).attr('placeholder'))
		});
		$("input").keydown(function(e){
			if(e.keyCode === 13){
				console.log('搜索关键词为',$(this).attr('placeholder'))
			}
		})
		$("input").keyup(function(e){
			console.log("keyup",e.target.value)
		})
	});
	
</script>
<body>
	<input type="text" placeholder="请输入内容"/>
</body>
</html>